1. Field of the Invention
The present invention relates to a construction, having a damping device, which may be vibrated by, for example, earthquakes or wind. In particular, the present invention relates to a multistory construction having the damping device.
2. Prior Art
A construction having a damping device, such as high-rise building and multistory buildings are designed for safety and comfort in the event a horizontal force is imparted thereto by an earthquake or by wind.
Buildings in accordance with the prior art were designed so as to bear by rigid brace, earthquake resisting wall, and the like, horizontal forces (=displacement not too large, stress less than limit value). As a result, the maximum response depends on the damping ability of the building itself; the value of the maximum response is about 1.about.2% in a steel-reinforced concrete structure and about 5% in a reinforced concrete structure.
However, recently, a dynamic damping method called a "tuned mass damping method" or "tuned sloshing damping method" is used in high-rise buildings, towers, and the like, because the efficiencies of these constructions are not adequate.
In a dynamic damper, a spring mass damper type is added having a natural frequency similar to the natural frequency of the building. When the dynamic damper is provided in a building, vibration energy of the building is led to the addition type damper, and the apparent damping of the building is amplified in order that the addition type absorbs the vibration energy. However, this method has the following problems among others:
1. if the mass of the addition type damper is large, the efficiency is large; however, the mass of addition type damper is limited in practice; PA0 2. space in the highest floor, which is most valuable, is occupied by the damper, and is therefore lost; PA0 3. when an earthquake occurs, the amplitude of the addition type damper is too large to be absorbed or is absorbed inefficiently; and PA0 4. only the primary natural frequency is efficiently absorbed. PA0 (a) the quantity of vibration energy absorbed per unit of construction in accordance with this method is small since the method depends on the relative displacement between stories. Accordingly, many units are necessary to ensure sufficient damping: PA0 (b) the cost of construction in accordance with this method is high; PA0 (c) the maintenance of a construction according to this method is complicated; and PA0 (d) the weight of a construction in accordance with this method is large. PA0 (A) the cost of the damping apparatus is high and height of the damping apparatus is the large because of the steel wire cable 2 between pulley 3,3 is needed; PA0 (B) the horizontal part of the steel wire cable 2 between pulleys 3,3 is streched in the ratio of the same as the slanded part of the steel wire cable 2 when they are pulled. Accordingly, the streching loss of the steel wire cable 2 is large because of strech of the horizontal part of the steel wire cable 2 is streced as above, the transferal quantity of horizontal displacement of the construction having the damping device is transmitted to the damping device which is fixed on the foundation porttion of the construction; PA0 (C) the weight of the construction having the damping device is large and the cost of the construction having the damping device is high because of the many pulleys 3 are needed; PA0 (D) frictional losses are large in the transfer of the energy to the damping apparatus because many pulleys 3 are; PA0 (E) beams should be reinforced because each beam of each floor received axial force by the steel wire cables 3 which extends to horizontal direction; PA0 (F) maintenance is difficult because of the complexity of the mechanism.
Many damping methods are proposed, having strengthening materials which is provided at braces, earthquake resisting walls, and the like, as a method for amplifying the damping of vibrations in a construction more directly.
However, this method has the following problems, among others;
In order to provide a damping system to resolve the above problems, a method in which steel wire cables are tautly provided in constructions, steel wire cables are tautly provided on a building of the construction in a Z-configuration, as for example, as described in (JP-Heisei 2-1946).
This damping system is comprises, as shown in FIG. 29:
single steel wire cable 2, both sides of which are fixed at or near the top floor or nearly of the construction having the damping device 1, the middle portion of the steel wire cable 2 positioned at a lower floor;
pulley 3 provided at each junction between the beams and columns in each floor of the construction having the damping device;
an absorbing apparatus for absorbing displacement of the middle portion of the steel wire cable 2; and
steel wire cable 2 provided around alternate pulleys 3, so as to zigzag across the face of the building the steel wire cable 2 cross itself.
However, this damping system has the following problems; among others: